Is it possible to set the pivot point origin of an object in BGE with python
When you mean the object's origin: No, you can't (and it makes no sense).

When you mean the rotation center, you can:


combine the rotation with a translation (= orbiting)
parent the object to another that acts as rotation center. Turn the parent rather the child.


When you mean the pivot point of a a rigid body constraint, I do not know. The API does not look like you can. An alternative would be to remove the current constraint and create a new one with the pivot at the new location.